Stock flow



June 5, 1956 BEAQHLER STOCK FLOW Filed July 18, 1952 4 Sheets-Sheet l E FE I7 ZLE Edward E. Beacfz ier June 5, 1956 E. D. BEACHLER 2,748,670

STOCK FLOW Filed July 18A, 1952 4 Sheets-Sheet 2 ETI/*E ZZLET Edu/ara D Bean/z [er E ZLZ77E June 5, 1956 E. D. BEACHLER 2,748,67@

STOCK FLOW Filed July 18, 1952 4 Sheets-Sheet 3 Edu/aro D Bead/22er June 5, 1956 E. D. BEACHLER 2,748,670

STOCK FLOW Filed July 18, 1952 4 Sheets-Sheet 4 Edward B. Beach [er United States Patent 'O STOCK FLOW Edward D. Beachler, Beloit, Ws.,.assignor to Beloit Iron Works, a corporation 'of Wisconsin Application July 18, 1952, Serial No. 299,692

11 Claims. (Cl. 92-44) The Vpresent invention relates to .a stock liow Vmethod and apparatus, and more particularly, to such method and apparatus wherein .optimum flow control conditions are obtained at high speed operation and wherein the harmful effects of entrained or entrapped air in the 'stock are minimized.

Although it .was recognized in vthe art that very substantial amounts of entrapped or entrained air in the stock tended to produce irregularities and defects in the jpaper web, 'it has been .generally understood vin the art that the problem of entrapped air was fairly well taken care of if the presence of entrapped air in the stock in 'the vhead box did not appear to be .quite noticeable. The instant invention lis based to a substantial extent upon the discovery that so-called hidden or small amounts of entrained air in the stock are responsible for numerous other operational diliiculties in paper machines.

For example, in the usual paper machine design, the

head box may have a capacity of perhaps of the fan pump vdelivery in gallons per minute. Accordingly, relatively minor fluctuations in the fan pump delivery .are reflected in the head box in the form ,of relatively vlarge fluctuations in the stock level. This phenomenon was more or less accepted in the paper industry as a necessary evil resulting from the economic compact designV of the head box coupled with what was believed to be unavoidably small fluctuations in the fan pump delivery rate. These fluctuations in the head box stock level have now been found by me to be reflected quite clearly in the form of variations in the texture and other physical properties of the web vdeposited on the forming wire. After long and elaborate studies of numerous paper machines, I have found that irregularities in the paper web may be traced to fluctuations in the head box level during operation, which were heretofore thought to'be insignificant in extent. Paper webs of extremely superior uniformity maybe obtained by the use of a fixed, constant-ly maintained, head box stock level lwherein substantially less than the previously permitted lluctuations are maintained. In fact, l have found that it lis possible to select and maintain a predetermined stock level Lin a head box, which level is within the range of :fluctuating levels heretofore maintained during operation of ,such head box, so as to obtain paper webs of vsubstantially superior properties, far superior to the best properties heretofore obtained while ordinary fluctuations were'taking v,place in the stock level.

In other words, it can be demonstrated .that maintenance of a stock level at, for example, 11 inches, plus-or minus 1/4 inch, may result in .the formation of paper webs having properties that are substantially superior to those vproperties obtained in webs produced while .the stock level averaged 11 inches but luctuated from perhaps 8 to 14 inches. Also.. the properties of webs obtained `by vholding `the level, in vaccordance with my finvention, at perhaps 11 inches, plus or minus 1/4 inch vare far vsuperior to those obtained holding the level 'at perhaps 10 inches, plus vor minus V4 inch. It willthus be ,ICC

appreciated that my invention provides a control means for paper machine operation that was heretofore unappreciated.

In addition, the control means which my invention provides are such that production on an ordinary paper machine may be doubled or even tripled without .the loss of the `improved control which I have just described.

in essence, my invention provides for stock ilow wherein the minimum amount of air is entrapped Vas a result Yof .Conducting the stock from one location to another in the machine and the harmful effect of that minimum amount of entrained air is, in turn, minimized by the lmanner in which the stock ow is accomplished from one location to another, in accordance with the prin- ,c-iples of my invention. It will be appreciated that all paper machine stock, being exposed to air as it is at several places ,in the paper machine, must inherently have some air entrapped therein.

In general, my invention embodies four operational features, each of which may, alone, produce a very noticeable ,effect lin the paper machine operation, but two or more of which, in combination, appear to produce even a more unusual improvement, and the optimum operating conditions call for the use of all four of these operational features.

The first of these features, is based upon the discovery .that one of the principal causes of the formation ,of .lumps in the stock is the action of entrained air the stock vin .lateral (non-vertical) reaches of the stock -ilow conduits. It appears that in lateral reaches of such cond-.uits the entrained air tends to rise to the surface of the stock flowing therethrough and to coact with other bubbles .of 4entrained air rising to the top to form, presumably rst a foam-like material, and subsequently a slime, whereby impurities, fibers, and the like are collected at the tops Aof ,such conduits. I have found that the collection of this slime or `sludge (which frees itself in the form of particles or lumps which interfere with uniform operation) may be substantially avoided by constructing all lateral reaches of vthe stock conduits so that the roof p0rtions thereof yare inclined upwardly at a slope suicient to lpermit or cause entrained air to move forwardly and upwardly with the flowing stock. I have found that the slope of such incline is preferably at least 1 inch per linear foot and most preferably at least about 1% inches per foot, in the direction of stock flow, as I disclosed in my copending application Serial Number 215,543, led March 14, 1951, and now abandoned, of which this is a continuation-in-part.

In general, paper machines are designed so that the maximum production rate is approximately three times the minimum contemplated production rate. As a rule, minimum flow rates of not less than approximately 11/2 feet -per second are contemplated in such designs, so that the flow rate will be sufficient to maintain the stock 'bers in suspension, but the maximum flow rates may be substantially greater than this figure. As another feature of my invention, I have found that if flow rates of 9 feet per second or more are used in one or more stock conduits, it is not necessary to incline the horizontal reaches thereof, as just described, in order to avoid the formation of 'lump-forming sludge deposits on the roof kportions of the conduits. In other words, I find that itis necessary to raise stock streams flowing at 11/2-9 feet per second, so .that ythe Atops of such streams are raised at a rate of at least about one inch per linear foot in order to avoid sludge formations along the conduit roofs; but, in `the event that conduits may not be conveniently provided for effectively raising the tops of stock streams, as described, then it is necessary to induce stock ow in such conduits at rates .of 9 vfeet per second or more. As will be appreciated, ow rates of 9 feet per second at various parts in a paper machine may be handled easily, but in certain other parts of the paper machine, a flow rate of 9 feet per second is out of the question.

A second particularly important feature of my invention resides in the avoidance of waterfalls in the white water system. Heretofore, the practice in collecting white water in the wire pit has been to permit the water co1- lected in the save-alls to fall freely down the save-all spouts into the wire pit and the water collected in the seal pit is pumped into conduits which permit the free fall of water into the wire pit. I have found that this customary, and rather obvious, way of collecting white water in the wire pit has the extremely undesirable effect of gathering or entrapping an excessive amount of air, which greatly accelerates the formation of slime in those portions of the stock conduits, such as the horizontal reaches, which are peculiarly adapted for the collection of slime. As I have mentioned, the amount of air ordinarily entrapped in the white water during the dumping of the same into the wire pit from the save-alls or the seal pit has been heretofore disregarded, or at least assumed to be so negligible that it could not possibly produce an undesirable effect in the operation of the paper machine. I have found that this is not the case, and that numerous defective features of paper machine operation may be attributed to this so-called hidden amount of entrapped air.

In accordance with my invention, no waterfalls are employed in transferring stock from one pool or pond to another, such as the transfer of stock from the save-alls or the seal pit to the wire pit. Instead, I provide for uid communication between, for example, the save-all and the wire pit so that a water leg may be maintained between the two and levels of liquid maintained in each. I use the term water leg in contradistinction to the concept of free falling liquid or a waterfall, in that a water leg is a solid continuous enclosed fluid body which communicates with two different larger uid bodies or ponds of stock. I use the term pond herein to designate generically all such bodies or ponds in a paper machine, as contrasted to the specific use of the stock pond in the head box.

Also, I use the term stock herein to mean rich stock as well as the extremely dilute stock, generally referred to as white water in the paper machine art. For example, the stock in the stuff box or stock box may have a concentration of about 31/%, the stock entering the head box may have a concentration of approximately 0.25%, and the stock generally designated as white water may have a concentration of only a small fraction of a percent. In general, I have found the behavior of stocks having the aforementioned different concentrations to be approximately the same for the purposes of my invention.

A third feature of my invention is based upon the discovery that it is possible to remove, or permit the escape of a very substantial amount of entrapped air in the white water in the wire pit by increasing the necessary flow of white water therein to at least a distance greater than the length of the wire pit. Heretofore, the seal pit for the suction box drop legs and the save-all inlets to the water pit dumped the white water therein and it flowed directly down into the wire pit discharge. I have found that it is of appreciable importance in effecting the removal of a maximum amount of air from the stock, even though that air is substantially below what was heretofore thought to be the maximum amount of harmproducing entrained air. I have found that by lengthening the travel of the white water in the wire pit, it is possible to remove this additional amount of entrained air.

As a fourth important feature of my invention, I have found that a very substantial amount of harmful air has been caused to enter the stock flow system by the stuff box operation heretofore used. Heretofore, it was the common practice to feed stock from the stuff box into the system through a weir or some other type of measuring device which necessarily involved a waterfall. I have found that such a waterfall results in the collection of a very substantial amount of harmful entrapped air in the stock. Accordingly, I provide a stuff box arrangement wherein a stock or water leg is provided between the fixed level in the stuff box and the inlet to the fan pump.

It is, therefore, an important object of my invention to provide an improved stock ow method and apparatus whereby the entrapment of air in the stock is minimized and the harmful effect of entrapped air in the stock is also minimized.

It is a further object of my invention to provide a method of conducting stock via a water leg from one pond to another in a paper machine, that comprises drawing a stream of stock from below the level of one pond to below the level of the other, confining such stream in a closed system between said ponds, and raising the stream top at a rate at least sufficient to prevent air accumulation thereat during all lateral stream travel.

It is another object of my invention to provide an improved method of conducting a stream of stock through a given amount of lateral travel to a pond in a paper machine, that comprises flowing the stream in a pipe at a minimum linear velocity of ll/z feet per second and raising the top of all laterally directed stock stream portions not flowing at at least 9 feet per second at a rate of at least one inch per foot, and preferably ll/z inches per foot, in the direction of travel.

It is yet a further object of my invention to provide an improved method of and apparatus for operating a white water system in a paper machine, in accordance with the principles described herein.

It is yet another object of my invention to provide an improved method of and apparatus for operating a paper machine stuff box, in accordance with the principles described herein.

It is still a further object of my invention to provide, in a paper machine, a chamber for retaining a stock pond, a conduit communicating with said chamber for conducting stock ow vertically and laterally, and flow control means in said conduit for maintaining a stock pond in said chamber of predetermined level above the communicating conduit, all the lateral reaches of said conduit having roof portions inclined upwardly in the direction of stock ow at a slope of at least one inch per foot.

It is still another object of my invention to provide an improved method of an apparatus for operating a paper machine wherein the piping is arranged to avoid waterfalls and to avoid the collection of slime along the tops of horizontal reaches of conduits.

Other important objects, features, and advantages will become apparent to those skilled in the art from the following description and drawings of preferred embodiments of my invention.

On the drawings:

Figure l is a side elevational view of a paper machine embodying my invention, with parts shown diagrammatically, in section, and fragmentarily;

Figure 2 is a top plan view taken substantially along the lines II-II of Figure l;

Figure 3 is an elevational sectional view taken substantially along the lines III-III of Figure 2;

Figure 4 is a sectional elevational view taken substantially along the lines IV-IV of Figure l;

Figure 5 is an end elevational view taken from the right hand side of Figure l and 2, showing the head box piping arrangement embodying my invention;

Figure 6 is a top plan view showing a modified fan pump piping system embodying my invention; and

Figure 7 is a sectional elevational view taken substantially. along the lines VII-VII of Figure 6.

As shownV on the drawings:

' In Figure 1, the reference numeral- 10' refers generally toa paper machine having a piping arrangement for stock flow embodying my invention; In thev paper machine the stock flows from a head box 11 onto the forming wire W which is trained about a breast roll 12 at the head box and a couch roll 13 at the opposite end. For the sake of clarity, many details of the paper machine structure, such as the various guide rolls Yand turning rolls for the wire W, have been omitted from the drawings, since their particular arrangement is not a part of the instant invention and such arrangements are welly known to those skilled in the" art.

Considering first the flow of white water through the save-'all system, as is well known in the art, at the breast" roll end of the wire W water passes rapidly out of the stock through the wire W and falls into the save-alls, designated by the reference numeral 14 generally and shown only diagrammatically in'v Figure l. In general, the" save-alis 14 comprise open' topped tray-likeV conduits which catch the water falling through the wire W' and are slanted slightly so as to divert the water to the'downspouts 1S and communicate with thel wire pit 16 via laterally extending conduit portions 17 entering the side wall 16a of the wire pit 16 and having roof portions or tops 1S' which are inclined upwardly in the direction of stock flow; that is, the roof 18 is inclined upwardly from the point at which the conduit 17 communicates with the vertical portion of the' downspout 1'5 to the' point' at which the conduit 17 communicates with the wire pit side wall 16a. p

The upward slope of he room 18 isA at least that sufficient to prevent appreciable accumulation of air at the top of the stock or white water stream flowing through the conduit 17, which slope has been found to be at least about 1 inch per foot and preferably at least about 11/2 inches per foot. The floor of the conduit 17 may be substantially level and aligned with the wire pit floor adjacent thereto, as shown herein, but the top of this horizontal reach or lateral duct work 17 must, in ac-- cordance with the invention, be upwardly inclined or the accumulation of air bubbles, foam, etc. will ultimately built' up slime and sludge on the roof 18. The sludge tends to break loose in chunks during. operation so as to cause numerous operational difficulties, as will be appreciated by those skilled in the art.

I also provide valve means 19 in each downspout 15 below the level L-l of the white water in the wire pit 16. Preferably these valve means 19 are a damper type valve adapted to effect a substantial pressure drop in the stream of white water by restricting the ilow thereof. The valves 19 are adapted to restrict the stream flow to the extent necessary to maintain constantly a level L*2 in the save-all 14, which involves developing a pressure drop across the valve 19 equal to they head of water equivalent to the difference between the wire pit level L-1 and the save-all level L-Z. Also, the save-al1 14 and downspout structure is arranged so that the downward stock flow, taken with respect to the save-all level L-2 (or the top of the white water pond in the save-all 14) is preferably not more than about 1 foot per second, and most preferably not more than about 0.5 foot per second, so that a whirlpool or vortex will not be formed to draw air into the stock.

The valves 19 may, of course, be controlled manually so asl to maintain the necessary pressure drop thereacross, or they may be controlled automatically by suitable control means responsive to the save-all level L-2. For example, a oat actuated control means, designated generally by the reference numeral 2t), and shown diagrammatically, in Figure 4 may be used to control the actuation of the valve 19, so as to maintain a predetermined level lf2 in the save-all. As will be appreciated, the valves 19 are positioned below the level L-l of theV wi'reepit 16,

so that? there is no tendency to draw a Vacuum in the d'ownspout 15 during actuation of the valve 19.

It' will' thus be seen that', in general, the arrangement for conducting white water from the save-all 14 to the' wire pit 16 is one wherein there are no free waterfalls and a dynamic, as contrasted to a static, water leg is maintained between the pond of white water in the saveall 14 and the pond of white water in the wire pit 16, via the downspout 15 and valve 19 arrangement. In addition, the piping arrangement is such that substantially all'of the lateral or horizontal reaches in the piping arrangement have upwardly inclined roof portions, as described, and

substantially all of the downwardly directed reaches of such piping are directed downwardly in a vertical direction. I use substantially advisably, since it is apparent that the small portion of the piping designated by the reference numeral 15a does not conform with the general rules for piping arrangements of the invention. This smail' section 15a has been illustrated herein for the purpose of showing that suitable operating conditions may be obtained, even though a very small section of a horizontal reach does not have an inclined root` or a very small section of a downwardly directed conduit is not vertical. As will be appreciated, there may be certain piping arrangements which cannot be avoided or which can be avoided only by extremely impractical means. If one or two of such defective piping features is employed the advantages of my invention may still be realized, since the net effects of such defects in an extremely minute portion of the overall piping may be insignificant. However, it is by far more advantageous to carefully avoid all, or at least all significant defects of this type in the practice of my invention, since I have found that only la single defective point maybe a source of very great trouble.

The advantages of my invention include greatly improved flow control so that the particular head box level which gives optimum results may be maintained continuously. As will be appreciated, only a single slug of air or chunk of sludge developed at such a defective point and passing through the fan pump may result in an appreciable disturbance of this level, and only occasional disturbances of this nature may quite easily render the entire control ineffective.

Also, it should be mentioned that the presence of the defective piping at 15a, as I have chosen to illustrate it, is at a point most remote from the fan pump, thereby rendering this defect least harmful in nature. The defective piping at 15a should, however, in the most preferred embodiment of my invention, be altered so as to comply with the general piping arrangement structure of the invention; for example, by extending the save-all sides so' that a straight vertical draw from the save-all bottom could be arranged.

As still another aspect of my invention, I desire to `refer to the structure 21 in Figure 4 showing, at the position opposite location 15a, an upwardly inclined roof terminating with a bleed-off valve and merging with a vertical downward reach. In such a structure the slope of the' top of the stock stream changes abruptly from plus to minus. I have tested such structures in paper machines and I have found that there is a very great tendency for slime to collect uponthe conduit roof whereat the stream slope changes from more than zero to minus one (vertif cally downward); but that formation of slime thereat may be avoided merely by maintaining a substantially constant air bleed at the point. There are, of course, certain practical limits to the number and extent of such installations in a paper machine, but such an arrangement may be found to be more practical than extensive re-arrangement of the piping. It will thus be seen that all downward piping should not only be vertical but should also be positioned directly under bodies of stock having their tops exposed to air for venting purposes, and should provide direct communication vertically from such piping to an air-exposed top surface of a stock body or pond.

The white water falling through the wire W and into the save-all 14, in passing through the air and in splashing in the save-all 14, picks up or entraps an appreciable amount of air. In the instant invention, additional air pick up is prevented from this point on by the elimination of additional waterfalls in the paper machine stock llow. Also, the instant invention provides for the release of substantial amounts of the air thus entrapped and the elimination of substantial amounts of the foam or froth which may result from the splashing in the save-alls, for example.

As is best seen in Figure 2, the wire pit 16 receives the white water from the vertical downspouts and the lateral conduit portions 17 in side channels 22 and 23, which are separated from a central longitudinally extending channel 24 by means of longitudinally extending walls and 26 respectively. The lloors 22a and 23a of channels 22 and 23, respectively, slope gently in a forward longitudinal direction with respect to the paper machine to direct the white water flow forward as shown by the arrows. At the forward end of the channels 22 and 23 there are provided apertures 25a and 26a in the walls 25 and 26, respectively, for fluid communication between the central channel 24 and each of the side channels 22 and 23.

The various walls of the wire pit 16 and the other structural portions of the wire pit 16 are formed of grout or mortar, as is the usual practice in paper machine construction. As is best seen in Figure l, each of the apertures 25a and 26a in the grout walls 25 and 26, respectively, is flush with the channel tloors 22a and 23a respectively and is submerged substantially below the level L-l in the wire pit 16. The portions of the walls 25 and 26 extending upwardly over the apertures 25a and 26a, respectively, extend above the level L1, and overflow gates 27 and 28 in the wire pit forward end wall 16b effectively maintain the level L-1 below the tops of the walls 25 and 26 and also etlectively remove foam or the like floating material on the white water surface. Such material spilling over the top of the gates 27 and 28 may be dumped in the sewer, or reprocessed, if desired.

In the channel 24, whose oor 24a slopes gently backward in reverse to the slope direction of the floors 22a and 23a, the white water ows rearwardly of the machine 10 and into a lower basin 29. During the entire travel of the white water from its entrance into the wire pit 16 from the conduit 17 up to and including its owing into the basin 29, the white water top surface is uncovered to permit maximum release of entrapped air. Heretofore the practice was to permit white water to fall into the water pit and then ow through the shortest possible path directly to the lowermost discharge portion of the wire pit, which would correspond to the basin 29 in the instant structure. In the instant structure, however, the walls 25 and 26 are so arranged that the middle channel 24 is substantially the longitudinal dimension of the wire pit in length and an appreciable amount of flow (even from the nearest inlet conduits 17) must take place in the side channels 22 and 23 before the white water enters the channel 24. All white water must ow at least the longitudinal dimension of the wire pit 16 before being discharged therefrom, and preferably a distance appreciably more than the longitudinal dimension of the wire pit 16. As will be appreciated, the maximum travel path in the wire pit depends upon the member of walls such as the walls 25 and 26 which may be installed, as a practical matter, in a wire pit to accommodate suitable paper machine operation. In the instant structure, about twice the longitudinal dimension of the wire pit 16 is the maximum travel path for the white water, and lit has been found that, in most instances, this is a suciently long travel path, although three or four times the longitudinal dimension of the wire pit may also be found to be a suitable travel path.

In an arrangement such as the instant wire pit arrangement, wherein the stock travel path averages about 1% to 2 times the longitudinal dimension of the wire pit, it is preferable to so design the wire pit that the necessary amount of white water may pass therethrough, and the rate at which the stock ows laterally (or longitudinally) in the wire pit should not be substantially in excess of 11/2 feet per second. Preferably the white water ow rate is about 1/2 to 11/2 feet per second in the wire pit 16. If the ow rate in the wire pit 16 is too rapid, the turbulence of the white water at the top surface thereof may cause additional entrapment of air. As previously mentioned, the minimum flow rate of strong or concentrated stock in pipes is about 11/2 feet per second, in order to be certain of maintaining a uniform liber suspension therein; but white water is such a dilute stock that it need not be caused to ow quite as fast. As will also be appreciated, the ow rate in open topped conduits such as the wire pit and the save-all is maintained for the purpose of permitting the release of entrapped air and there is no problem of slime formation along the roof of the conduit.

As is best shown in Figure 4, the white water flows from the basin 29 through a lateral discharge opening 30, through a laterally extending grout conduit 31 and into the intake chamber 32 to the fan pump (not shown). The oor 34 of the laterally extending conduit 31 is sloped gently downwardly, but the roof 35 of the laterally extending conduit 31 is inclined upwardly in substantially the same manner that the roof 18 of the laterally extending conduit portion 17 is inclined upwardly. It will thus be seen that the roof portion 35 of the entire lateral reach here involved is inclined upwardly in the manner and for the purposes hereinbefore disclosed in detail. Also, the conduit 31 is arranged to provide a continuous water leg from below the level L-l in the wire pit 16 to below the level L-4 in the fan pump intake chamber 32. Actually, the level L-1 and the level L-4 are substantially the same. There is a slight drop in the white water level as it passes from the side chambers 22 and 23 to the middle chamber 24 in the wire pit 16, and there is another slight drop as the white water passes from the middle chamber 24 to the fan pump intake chamber 32, when the white water is flowing in normal operation of the paper machine 10.

Referring now to the arrangement involving the seal pit 36, which is shown fragmentarily and diagrammatically in Figures l, 2 and 3, in the paper machine 10 underneath the wire W near the couch roll 13 there are provided a plurality of flat boxes or suction boxes 37 which closely underlie the wire W and operate to de water the web thereon by the application of suction forces to the bottom of the wire W. Each tlat box 37 is provided with one or more drop legs 38 through which a vacuum is pulled in the flat boxes 37 and which extends downwardly a substantial distance to the seal pit 36.

As is shown best in Figure 3, each drop leg 38 extends into the seal pit 36 so that its lower extremity is submerged a substantial distance below the white water level L-S that is maintained in a central longitudinally extending chamber 39, defined by a pair of longitudinally extending walls 40 and 41, the seal pit back wall 36a (Figure 2) and a laterally extending partition wall 42 (Figure 2). As will be appreciated, the reduced pressure in the drop leg 38 causes a white water level to be maintained r therein that is substantially higher than the level L-5 in the middle chamber 39.

The four outside walls 36a, 3611, 36C and 36d of the seal pit 36, and the inner walls 40 and 42 all extend to substantially the same height. The remaining inner wall 41 does not extend upwardly as far and its top has a knife edge structure 43 which slants away from and down from the inner chamber 39, so that white water overflowing at the level L-S from the inner chamber 39 to an outer chamber 44 may flow downwardly to the slightly lower level L-, which is the white water level for the retains remainder of' thesal pit 36.4 The" knife edge"arranglv`v` nient `43fniinimizesthe`waterfall 'effect 'obtained byflowing'vw'alt'e'r over the top of the'jwall 41. Although"a'sub` mergedV discharge forv the inner chamber 39 wouldv be preferable in"v avoiding completely any waterfallV effect, certain operational diiiiculties would be involved because ofthere'duced pressure inthe drop legs 38. In general,` it ispr'eferable to employ a seal pit arrangementk whereby thereis no' possibility that the seal pit might be pumped andintofthe"thirdchamber 116,' whence the white water ws'the' fully length of' the`r seal pitl 36I (like the flow in" tlie wire; pit 16) and into the se'al pit purnp suction di" iitig inegi (as best' sfiiowniii Figure 2,). From th@ seal pit pump 4S theiwhite/wateris. pumped rearwardlyiof the paper machine 10 through a" rst lateral reachfofr' pipingi`9, then through second lateralreach of pip 5(l"w hi'ch extends: laterally` beneathy the wire pit'l", next through a third laterfal reachA of piping 51 which extends' alongthe' side of the wire pit and to the rear therevoilai'id rally to a fourthl lateral reach of piping 5.2',Y whieh serves as` a header for three' laterally/ extending inlet pip'es:.53 The" inlet pipesl 53 extend through the rear' end wall 16CY ofthe wire pit I6 at spaced kintervals s'onas to permit a relatively uniform distribution of ,the se `al' pit White water gow entering at the back endof the wi pity 1'6". The whiteV water flows" therefrom in subof'white water from the save-alls, once it has`V` entered the wire pit 16.Y A K Y i n As can'b seen from Figures and 2 all of theV lateral reaches of piping 49,` 50, S1', A52 andr53 are upwardly inclined the'direction of rate of incline being seal pit pump, iivillbe` appreciated that white water isV i wiiiigiawairaa iii@ saai pit 36 from basuras-'ian 1 6 therein and is piped upwardly to the wire 1 6, belowY thelvvel therein, lso'ythat again a water leg rnin ined b en the `'two bodies orY white` .ate'izV Referring now td the operation o f the s tui 56, as best shown in Figurey l, it` will bevseeriwtliat stui Aboil: 56 is posifioijki substantially Bove the v v'ii wsa to provide for gravity',k flow of sitor'c'k from the stu box 56 to th'e fii pump intake'pcharnber 32, via the stuit box drop leg 57. Inl the operation 'of the stuit box 56 s't'oc'li" is pumped upwardly from die refiners (not shown) thru'gh the pipe 58 and into'the bottom of the stuff box 56. The stuit bx level L7 is maintained by means of an over iw partition wa'll 59, which permits the flow of stock thereov'er and intoa b'o'ttomdischarge pipe 60 which leads tothe machine stock chest (not shown)JY A partition wall 61 positioned between the stock inlet 5,8 and theV drop leg dischargeu57 extends upwardlyV less than the height of the over now wall 59, so as toA be lsubmerged at all times but to increasethe travel path of the stock in the stuit box. Preferably control means, as indicated diagrammaticallyat 62,- are provided 1for operation of a gate in the over flow partitionwall 59 so as to give better level 4control instuif box 56, g

It will thus be seen that as the stock direction 'of ow 10 changes fron'i'upwardldi'rection flowing out of thepipe 58'todwnwa'rdf'direc'tiii owingint the pipe 57 th'etop surface Aof the stock streairi.v isven'ted or"expos`ed tothe air'. 'Thedownw'ardly directed stock stream in thepipe 57 ilows subst" tilly' vertically from' directly belowrv an open topped or"v`erite'dpo'rti'or of stock down to a control valve' 63, whieh'nia'ybe us'ed to control the stockY flow, preferably soasfto'fmaintai the"rate"of vertical stock ow from they stuff boxI at less than ll foot pers'econd and preferably lss than aboutYr O55 foot per secondptkbr The" stock tlow'sthrough the control valve 63' (below'the'le'vel'L-4) andl then' through a` lateral reach of piping 64,' inclined as the reasons hereinbeforeVV mentioned;`

hereinbe'fore'described upwardly in the direction of `ilow, which leadsintothe bottom of the fan pump intake chain# ber 32. Mixing of the rich stock with the? white' watei" thus takes place in the fan pump intake charnber32,VV as well as in the fan pump 33.

Communication between the' fan pump intakechamber 32` and the fanV pump 33 on the suction side'is providedY by'means of a' laterally extending conduit 65, which has an upwrdly'inclined roofportion 66 of the structure hereinbefore" described.

As can be seen, the fanY pump discharge 33 is connected to a first laterally and upwardly inclined reach of piping' chine' 1'0 and is connected with a third lateralreach of piping 6'9'which conducts the stock tola point directly below the head b'ox 11 and into the T-iitting 70.

From the T-tting 7i) the stock stream, split in two substantially e'qualhalves, is directed Athrough the oppositely extending lateral reaches of piping 7l, '71, each ofV which is connected by means of elbows 72, 72 to vertically extending'pipes 73, 73.' Each of the vertically extending pipes 73, 73 has an elbow 7d, and these elbows 74, 74 are'connected to the head box on opposite sides thereof near the bottom. l

The head box`11 has the same structural arrangement a's that described in detail in my copending application Serial No. 215,543, filed March 14, 1951. The box 11r is mounted onsp'aced supporting posts 7S, '7,5 which rest on the ilo'or F. The bottom rear inlet to the head box 11 is provided with a cross flow stock distributor indicated generally by the reference numeral 76, which comprises a lower distributor casing section 77 defining a pair ofv open topped cross ow conduits beneath the head box 11, which are co-extensive across the entirey width o'f tiie'lied Box inlet.

The rear diie 78 of the open topped conduits is connected to one of the elbows 74 by means of a conduit 79 and the front one Si) of theopen topped conduits is cieted with the other elbow 74 by means of a conduit 81. A recirculating line 82 ai'or'ds communication between Athe rear open topped conduit 73 and the top portion of the closed conduit 81, for re-circulation purposes; anda pipe 83 in like manner aords communication between the front open topped circuit and the top of the closed conduit 79 for recirculation purposes.

In particular, it will b'e noted that all of the lateral reaches f the piping from the fan pump 33 to the open top 'conduits 78 and 80 have the roof portions thereof inclined upwardly in the direction of flow at slopes corresponding to those hereinbefore described in detail. Even the elbows 72 and 74 have the roof portions thereof inclined upwardly to 'the extent described, so that there will be no horizontal roof portions. Also, the stock ow from the fan pump intake chamber 32 to the head box 11 involves ow from below the intake chamberlevel L-4 to below the head box level L-3.

yRefer-ring now to Figures 6 and 7, which show a modified pipi-ng arrangement for the fan pump system, it will be seen that in these figures those elements which function substantially as the corresponding elements in the previous figures function have been designated by the prime of the same reference numeral. The fan pump 33', in Figures 6 and 7, discharges into a generally arcuate reach of piping which substantially reverses the direction of ow, being generally designated by the reference numeral 84. The piping 84 is connected to a lateral reach of piping 69' which corresponds to the piping 69 shown in Figures l-S inclusive, and the piping 84 also has a connection 85 extending substantially horizontally from the fan pump discharge. The connection 85 is, in turn, connected to a generally L-shaped horizontal reach of piping for reversing the direction of stock ow therein, generally designated by the reference numeral 86 (Figure 6). The L-shaped section 86 has a control valve 87 therein, which may be used to control the stock ilow from the fan pump 33' through the connection 85 and the piping 86.

At the bottom of the stuit box drop leg 57 below thc control valve 63', there is an elbow 88. The end of the piping 86 not connected at S5 communicates with the elbow 88, via a welded joint in the curve portion of the elbow. lt will thus be seen that mixing between the rich stock from the stuff box and the stock diluted to the desired concentration for use in the head box may take place in the elbow 88 and the horizontal reach of piping 89 connected thereto.

The horizontal reach of piping 89 is connected to a downwardly sloped reach of piping 90 which directs the stock flow to an upwardly sloped inlet pipe 91 for the fan pump intake chamber 32', so that the enriched stock may be mixed with the white water in the intake chamber 32.

As will be appreciated, the intake chamber 32 in the piping arrangement shown in Figures 6 and 7 is in etect a downward extension to the basin 29 shown in Figures l, 2 and 4. The advantages of the structure shown in Figures 6 and 7 include the relatively short stock travel from the fan pump to the head box and a preliminary admixing of stock at the elbow 88.

As will be appreciated also, the piping 85, 86, S9 and 90 is not arranged so as to conform with the structure hereinbefore described, in that the downwardly extending pipe 90 is not vertical and the lateral reaches 85, 87 and 89 are not upwardly inclined. In this particular structure, however, it is necessary to pump the stock through the piping 85, S6, 89 and 90 at rates of 9 feet per second or more, since as was mentioned hereinbefore flow rates of 9 feet per second or more have been found to be suiciently rapid to prevent the harmful effects resulting from r.. air accumulation at the top of horizontally flowing streams of stock. Apparently, the turbulence in stock streams flowing at rates of at least 9 feet per second is such that no appreciable separation of air may take place. It so happens that ow rates of 9 feet per second may be maintained at various machine operating speeds in the particular rccirculating piping arrangement of Figures 6 and 7, in the piping sections 85, 86, 89 and 90, although flow rates of 9 feet per second or more may not be used in other portions of the piping.

lt will. of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

l. A method of operating a white water system in a paper machine having white water save-all and wire pit levels maintained therein so as to minimize the harmful effects ot' entrapped air in the white water and to have optimum ow control conditions, that comprises piping white water downwardly and laterally from below a save-all level to below the wire pit level through a water leg maintained by restricting the ilow therein at a til) point below the wire pit level so as to maintain constantly a save-all level, piping white water upwardly and laterally from below the seal pit level to below the wire pit level through a water leg maintained by restricting the tlow from the seal pit to maintain a seal pit level, and piping white water laterally from the wire pit discharge below the wire pit level at a rate to maintain a substantially constant wire pit level, the white water streams thus piped laterally being raised at their tops at a rate of at least l inch per foot of travel above the horizontal in the direction of travel.

2. A method of operating a white water system in a paper machine having white water save-all and wire pit levels maintained therein so as to minimize the harmful etlects of entrapped air in the white water and to have optimum ow control conditions, that comprises piping white water downwardly and laterally from below a saveall level to below the wire pit level through a water leg maintained by restricting the ow therein at a point below the wire pit level so as to maintain a constant saveall level, piping white water upwardly and laterally from below the seal pit level to below the wire pit level through a water leg maintained by restricting the flow from the seal pit to maintain a seal pit level, and piping white water laterally from the wire pit discharge below the wire pit level at a rate to maintain a substantially constant wire pit level, the white water streams thus piped laterally being raised at their tops at a rate of at least l inch per foot of travel above the horizontal in the direction of travel, and the water piped from the save-alls and the seal pit being caused to flow in the wire pit at a rate of 1/2 to ll/z feet per second for a distance of at least thc longitudinal dimensions of the wire pit before being discharged therefrom, and the rate of discharge from the pit being maintained at less than a downward velocity of l foot per second.

3. In a paper machine, a white water system comprising a seal pit for receiving water from the at box drop legs and adapted to maintain a water level therein, a wire pit also adapted to maintain a water level therein and positioned above said seal pit, a conduit having vertical and lateral reaches and affording uid communication between below the water level of said seal pit and below the water level of said wire pit, and pump means in said conduit to effectively retain a level in said seal pit and said wire pit and a water leg between the water levels in said seal pit and said wire pit, all the lateral reaches of said conduit having roof portions inclined upwardly in the direction of stock ow at a slope of at least l inch per foot.

4. ln a paper machine, a white water system comprising a save-all adapted to maintain a water level therein, a wire pit also adapted to maintain a water level therein and positioned below said save-all, a downspout affording fluid communication through downwardly and laterally extending reaches between the bottom of said saveall and below the water level in said wire pit, let-down valve means in said downspout below the wire pit level to effectively retain a level in said save-all and a water leg between the water levels in said save-all and said wire pit` a seal pit adapted to receive water from at box drop legs and to maintain a water level therein, said seal pit being positioned downwardly and laterally from said wire pit, a conduit having vertical and lateral reaches and attording fluid communication between below the level in said seal pit and below the level in said wire pit, and pump means in said conduit to effectively retain a level in said seal pit and a water leg between the water levels in said seal pit and said wire pit, all the lateral reaches of said downspout and said conduit having roof portions inclined upwardly at a slope of at least l inch per foot.

5. In a paper machine, a white water system comprising a save-all adapted to maintain a water level therein, a wire pit also adapted to maintain a water level therein and positioned below said save-all, a downspout affording uid communication downwardly and laterally bctween the bottom of said save-al1 and below the water level in said wire pit, let-down valve means in said downspout below the water pit level to eiectively retain a level in said save-all and a water leg between the water levels in said save-al1 and said wire pit, a seal pit adapted to receive water from the ilat box drop legs and to maintain a water level therein, said seal pit being positioned downwardly and laterally from said wire pit, a conduit affording iiuid communication between below the level in said seal pit and below the level in said wire pit, pump means in said conduit to eiectively retain a level in said seal pit and a water leg between the water levels in said seal pit and said wire pit, said downspout and said conduit having lateral reaches and all the lateral reaches of said downspout and said conduit having roof portions inclined upwardly at a slope of at least 1 inch per foot, a stuit box adapted to maintain a stock level therein, an inlet conduit communicating with said stuit box below the stock level and adapted to supply stock to maintain the stuff box level, an outlet conduit communicating with said stuit box below the level, a fan pump having its intake in communication with the other end of said discharge conduit, and a let-down valve in said discharge conduit positioned at a height below the eiective water head at said fan pump intake and adapted to effectively retain a stock level in said stuit box and a stock leg between said stuitE box and said fan pump intake.

6. in a paper machine, a white water system comprising a save-all adapted to maintain a water level therein, a wire pit also adapted to maintain a water level therein and positioned below said save-all, a downspout alording fluid communication downwardly and laterally between the bottom of said save-all and below the water level in said wire pit, let-down valve means in said downspout below the water pit level to effectively retain a level in said save-all and a water leg between the water levels in said save-all and said wire pit, a seal pit adapted to receive water from the at box drop legs and to maintain a water llevel therein, said seal pit being positioned downwardly and laterally from said wire pit, a conduit affording fluid communication between below the level in said seal pit and below the level in said wire pit, pump means in said conduit to effectively retain a level in said seal pit and a water leg between the water levels in said seal pit and said wire pit, said downspout and said conduit having lateral reaches all the lateral reaches of said downspout and said conduit having roof portions inclined upwardly at a slope of at least 1 inch per foot, a stuff box adapted to maintain a stock level therein, an inlet conduit communicating with said stuff box below the stock level and adapted to supply stock to maintain the stuff box level, an outlet conduit communicating with said stuff box below the level, a fan pump having its intake in communication with the other end of said discharge conduit, and a let-down valve in said discharge conduit positioned at a height below the eifective water head at said fan pump intake and adapted to effectively retain a stock level in said stuit box and a stock leg between said stuff box and said fan intake, a head box, a third conduit affording uid communication between said fan pump discharge and the bottom of said head box, all the lateral reaches of said downspout, said rst, said second, and said third conduits having roof portions inclined upwardly at a slope of at least 1 linch per foot.

7. In a paper making machine having a stock inlet, a looped web forming wire having an upper run receiving stock from the inlet, suction means acting through the upper run of the wire to dewater a web on the wire, drop legs draining said suction means, a seal pit receiving said legs, a save-all pan underlying said upper run of the forming wire, a wire pit beneath said pan, a stock box having a drop leg feed pipe, a stock pump having an inlet and an outlet, the improvements of conduit means containing vertical and non-vertical portions connecting the seal pit with the wire pit, the save-all pan with the wire pit, the

drop leg feed pipe with the pump inlet and the pump outlet with the stock inlet, said conduit means having all non-vertical portions provided with roofs which are inclined upwardly at least one inch per foot of length and said wire pit having an elongated open top flow path for iiuid from the seal pit and the save-all pan of greater length than the length of the wire pit and discharging into the stock pump inlet.

8. A paper machine cross-how stock distributor comprising a pair of open-topped flow conduits adapted to receive oppositely flowing stock streams therein, means establishing stock flow from said conduits through the open tops thereof to a paper machine inlet box, and stock iiow passages having lateral reaches for introducing stock flow into said conduits, all lateral reaches of said passages having roof portions which are inclined upwardly along the direction of travel of stock therethrough for preventing the separation of entrained air from stock iiowing through said passages.

9. in a paper machine cross-flow stock distributor having a pair of open-topped flow conduits adapted to receive oppositely flowing stock streams therein for introduction into the stock inlet box through the open tops of the conduits, the improvements which comprises stock ilow passages having horizontal reaches through which stock is introduced into said conduits and stock recirculation passages also having horizontal reaches establishing communication between said conduits, all the horizontal reaches of said passages having roof portions inclined upwardly along the direction of stock flow therethrough for preventing the lumping of stock ilowing through said passages and into said conduits.

l0. A paper machine cross-ilow stock distributor comprising a pair of open-topped ow conduits adapted to receive oppositely ilowing stock streams therein for discharge into a stock inlet box, stock recirculatory passages having lateral reaches and establishing communication between said conduits adjacent the ends thereof, stock ow passages having lateral reaches and communicating with said conduits, and stock flow passage elbows for establishing stock ilow from a source to said passages, all the lateral reaches of said recirculatory passages and said stock ilow passages having roof portions inclined upwardly along the path of stock ow travel therethrough at a slope of at least one inch per linear toot, and said stock ilow elbows having eccentric upper and lower curved surfaces to provide an effective upward slope of the elbow passage roof.

l1. A paper machine cross-flow stock distributor comprising a pair of open-topped tlow conduits adapted to receive oppositely owing stock streams therein for discharge into a stock inlet box, means establishing stock flow into opposite ends of said conduits, and means establishing communication between said conduits adjacent the other ends thereof for the recirculation of stock between said conduits, said last-mentioned means including stock conduits of reduced size and joining elbows having lateral reaches and having roof portions inclined upwardly along the path of travel of stock in all lateral reaches thereof for preventing segregation of air entrained in the stock and air collection in the stock passages and elbows as a consequence of stock iow therethrough.

References Cited in the ile of this patent UNITED STATES PATENTS 1,610,742 Bucking Dec. 14, 1926 1,708,434 Titft Apr. 9, 1929 1,717,223 Karlstrom .lune 11, 1929 1,943,180 Karlstrom Jan. 9, 1934 2,001,208 Minskey et al May 14, 1935 2,205,693 Milne June 25, 1940 2,345,647 Witham Apr. 4, 1944 2,347,130 Seaborne Apr. 18, 1944 2,509,822 Hornbostel May 30, 1950 

